Hydraulic System Troubleshooting - Piper PA-44-180 SEMINOLE Maintenance Manual

PRIOR TO STARTING ANY INVESTIGATIONS OF THE HYDRAULIC
SYSTEM, PLACE THE AIRPLANE ON JACKS. WITH THE AIRPLANE ON
JACKS, PULL THE EMERGENCY EXTENSION KNOB OUT THUS
PREVENTING THE BUILDUP OF UNNECESSARY PRESSURE ON THE
ACTUATING CYLINDERS AND CONNECTING HYDRAULIC LINES WHEN
THE GEAR IS RAISED OR LOWERED MANUALLY. FAILURE TO
COMPLY WITH THESE INSTRUCTIONS COULD RESULT IN THE
BUILDUP OF SUFFICIENT PRESSURE TO UNLOCK THE DOWNLOCK
ALLOWING THE GEAR TO COLLAPSE WHEN THE WING JACKS ARE
REMOVED. PRIOR TO REMOVING THE AIRPLANE FROM THE JACKS,
PUSH THE EMERGENCY EXTENSION KNOB IN, TURN ON THE MASTER
SWITCH AND SELECT GEAR DOWN, OBSERVE THAT ALL THREE
GREEN LIGHTS ARE ENERGIZED THIS WILL INDICATE THAT THE
LANDING GEARS ARE DOWN AND LOCKED. TURN THE MASTER
SWITCH OFF.
TROUBLESHOOTING.
Malfunctions in the hydraulic system will result in failure of the landing gear to operate properly. When
trouble develops, jack up the airplane (refer to Chapter 7) and then proceed to determine the extent of the trouble.
Generally. hydraulic system troubles fall into two types, troubles involving the hydraulic supplying system and
troubles in the landing gear hydraulic system. Chart 2901 lists the troubles which may be encountered and their
probable cause and suggests a remedy.
If it is found that the hydraulic pump is at fault and requires disassembly, it is
recommended that it be overhauled by an accredited overhaul facility. Pressure checks
with adjustments may be accomplished in accordance with instructions given.
PIPER AIRCRAFT
PA-44-180/180T
AIRPLANE MAINTENANCE MANUAL
— CAUTION —
— Note —
2B23
29-02-00
Page 29-05
Revised: May 15, 1989